A reaction vessel for use in producing large diamond crystals of good quality and yield includes a reaction volume and a reaction mass located in the volume. The reaction mass comprises a plurality of seed particles located in or on a surface in the reaction volume and a carbon source separated from the seed particles by a mass of metallic catalyst/solvent for diamond synthesis. The mass comprises alternating layers of carbon-rich and carbon-lean metallic catalyst/solvent which lie parallel or s...

The invention concerns a diamond body designed to enable thermal contacting with at least one source of heat (30) and presenting at least one recess (13, 15) defining an angular position in relation to the mechanical tensions generated by said or any source of heat (30). Consequently, the mechanical tensions generated at various temperatures, either, for example, by various expansion coefficients of the diamond body (12) or by the source of the heat (30) featured by one semi-conductor component,...

An electrode consisting of a substrate and a diamond layer applied to the substrate, in which the applied diamond layer is pore-free, and a process for producing a diamond-coated electrode, in which the process comprises at least the following steps: a) cleaning the surface of the substrate; b) seeding the surface of the substrate with a high diamond nucleation density; c) coating the surface of the substrate with diamond.

A diamond tool for the mirror-finish cutting of non-ferrous materials and a method of manufacturing the same are provided. The diamond tool has a main cutting edge and minute side cutting edges formed at the opposite ends of the main cutting edge so as to intersect the main cutting edge at an angle. The dept .DELTA. of chamfer of the side cutting edge is 1.5 to 5 times the depth of tears formed in the machined surface (0.1 .mu.m.ltoreq..DELTA..ltoreq.1 .mu.m) and the length l.sub.2 of the side c...

Crystalline diamond is grown on a substrate by placing the substrate on a nitride surface which completely covers a graphite support, creating an atmosphere of a gaseous carbon compound around the substrate, bringing the temperature of the nitride surface and the substrate to at least 600.degree. C., and subjecting the gaseous carbon compound to microwave energy suitable to cause the compound to decompose and produce carbon which deposits on the substrate and forms crystalline diamond thereon.

A mixed cut gemstone having a brilliant cut crown, a girdle and a step cut pavilion. The step cut pavilion contains four rib lines running from the girdle to a culet, which can be a line or a point. These rib lines subdivide the pavilion into four sides, which, if the girdle is shaped like a square, are equivalent, and, if the girdle is shaped like a rectangle, then any two opposing sides are equivalent. The pavilion contains a multitude of steps, which add to an elegant and classic look of the ...

A brilliant gemstone cut, having a crown, a girdle and a pavilion. The crown and the pavilion are both brilliant cut. The crown has a flat table shaped as an equilateral n-sided polygon, n corner facets and n upper girdle facets. The girdle is also shaped as an n-sided polygon. The pavilion has n rib lines, which converge at a culet, n lower girdle facets, n bezel star facets and double n number of corner facets. The rib lines subdivide the pavilion into n equivalent parts.

Diamond crystals may be grown by providing a source of diamond crystals, providing a plurality of growth centers defined by diamond crystals, mixing the source and growth center diamond crystals with a solvent/catalyst in particulate form to form a reaction mass, subjecting the reaction mass to conditions of elevated temperature and pressure suitable for crystal growth, and recovering the diamond crystals. The necessary supersaturation of carbon is achieved in the solvent/catalyst, at least in p...

In order to test whether a diamond has had a layer of synthetic diamond material deposited thereon, infrared radiation including radiation of wavelength substantially 7 .mu.m to 25 .mu.m preferably 7 .mu.m to 10 .mu.m emitted or transmitted by the diamond is observed, to detect differences between the compositions of different zones of the diamond.

In order to test whether a diamond has had a layer of synthetic diamond deposited thereon, the surface area of the natural part of the stone is measured by measuring the radiant-flux density of radiation substantially of wavelength 230 nm to 320 nm in an integrating sphere containing the diamond. This is compared to the total surface area of the diamond.